Failure to catch empty email on share plan

[raycarrick-ed]

Please complete the following fields as applicable:

What version of the DMPRoadmap code are you running? (e.g. v2.2.0)
v3

Expected behaviour:
if someone shares a plan and does not enter an email address they should get an error

Actual behaviour:
falls over with
NoMethodError (undefined method email' for nil:NilClass): app/controllers/roles_controller.rb:47:in create'

Steps to reproduce:
don't put in an email address on the share plan page and hit submit

[briri]

Probably related to PR #2874 which was an attempt to require the email address.

[briri]

think this is fixed. At least the controller has a nil check now